A few days ago, North Korea's national press agency has accused the former South Korean president of playing the key part in this story. He even looked forward to a time when peace on the divided Korean Peninsula would open up business opportunities inside North Korea.
Moon's team says the trip is about establishing a relationship between the two men.
Secretary of State Rex Tillerson and South Korean foreign minister Kang Kyung-hwa also held talks in Washington on Wednesday in preparation for the summit.
Moon pledged to stand firmly with Trump.
He said that the Moon government supported a balanced policy direction of engagement with and sanctions on the DPRK. He and his wife Kim Jung-sook will attend a dinner hosted by the Trumps at the White House later on Thursday.
"In that sense, its nuclear freeze will be the entrance and nuclear dismantlement the exit", he added.
The US goods trade deficit with South Korea has more than doubled since KORUS took effect in 2012, from $13.2 billion in 2011 to $27.7 billion in 2016.
Earlier on Wednesday at around 3:30 p.m, the South Korean government notified the North of the planned repatriation via the United Nations Command Military Armistice Commission.
The Trump administration has been trying to isolate the North Korean regime following a series of missile tests, including by persuading China - Pyongyang's main diplomatic ally - to help bring Kim Jong-Un into line.
Pyongyang claimed the United States was behind the decision to continue blacklisting North Korea for its alleged involvement in money laundering and "terrorist financing".
North Korea has shown no signs of wanting to restart talks on abandoning its controversial nuclear weapons programme.
Pyongyang has issued similar statements, meant to drive a wedge between the United States and South Korea, at a time when both countries are revisiting old issues under new administrations. And the more North Korea is isolated, the more it has innovated to get around sanctions. "The president has directed us to not do that and to prepare a range of options, including a military option, which nobody wants to take".
North Korea has already conducted nearly a dozen missile tests this year and is preparing to conduct another nuclear test aimed at producing nuclear weapons.